Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint=true and destructiveHint=false, and the description reinforces this with 'Read-only' plus the auth requirement (JWT or rk_ key), which is real behavioral context not present in the structured fields. It also decodes the meaning of key values (studio true = full access) and gives the enum-ish access values, though it does not say what happens when unauthenticated or on the free tier.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Auth and read-only status are correctly front-loaded and no sentence is pure filler, but the middle section is a dense run-on field dump ('and the ladder — free runs a day, the run pack (product_id, price, how to buy) and the Lab month (subscribe)') that resists parsing. Structure could be a short list rather than em-dash chains.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a no-parameter read with an output schema available, the description covers what an agent needs: auth requirement, safety posture, and the semantic meaning of the main fields. Remaining gaps are minor — the meaning of 'the ladder' and 'house'/'holder' access states is only gestured at.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The tool takes zero parameters, so there is no parameter semantics to add; the schema is empty and fully covered by definition. Baseline 4 applies.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description makes clear this returns the caller's own access/entitlement state, enumerating the concrete fields (studio, access, current_period_end, tier, full_access, run pack, Lab month). It also distinguishes the free-run-count case by pointing to free_tier_status. It falls short of 5 because the verb is implicit — it never literally says 'returns your subscription status'.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Usage is only implied: the auth prerequisite (JWT or rk_ key) is stated, and the final clause routes today's-run-count questions to free_tier_status. There is no explicit statement of when to call this versus page_me, studio_doors, purchases_mine, or subscribe.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.